Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests for blower motor operation in any speed setting.
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This step identifies if the HVAC control module is commanding the blower motor to operate at HI speed.
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This step verifies that power is being supplied to the blower motor.
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This step tests for a possible open in the blower motor ground circuit or for a poor motor.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference : HVAC Schematics DEFINITION: The blower motor is inoperative in all of the speed positions. | ||||
1 | Did you review the HVAC operation and perform the necessary inspections? | -- | Go to Step 2 | |
Does the blower motor operate in each speed position? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Important: Place the blower switch for the HVAC control module in the maximum speed position. Place the MODE selector in any position except AUTO. This will ensure a full speed condition when the blower motor is commanded to an ON position. Failure to do this may result in a misdiagnosis. Is the blower motor PWM parameter at the specified value? | 98% | Go to Step 4 | Go to Step 10 | |
4 | Use a volt meter in order to measure the voltage on the blower motor control circuit. Rotate the blower motor switch from the minimum speed position to the maximum speed position. Does the voltage vary between the specified value? | 0.4-4.0 V | Go to Step 5 | Go to Step 9 |
Does the test lamp illuminate and change intensity? | -- | Go to Step 6 | Go to Step 8 | |
Does the test lamp illuminate and change intensity? | -- | Go to Step 14 | Go to Step 7 | |
7 | Test the ground circuit of the blower motor control module for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 11 |
8 | Test the battery positive voltage circuit of the blower motor control module for an open or for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 10 |
9 | Test the control circuit of the blower motor control module for a high resistance, or for an open. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 |
11 | Inspect for poor connections at the harness connector of the blower motor control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
12 | Replace the HVAC control module. Refer to HVAC Control Module Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 15 | -- |
13 | Replace the blower motor control module. Refer to Blower Motor Control Processor Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
14 | Replace the blower motor. Refer to Blower Motor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | -- | Go to Step 16 | -- |
15 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2 |
